There are approximately 900 operators of transmission pipelines, 2,500 operators of distribution pipelines, and 220 operators of hazardous liquid pipelines. Operators are required to report accidents and incidents (i.e., releases of pipeline content) to the Department of Transportation's Office of Pipeline Safety (OPS) within 30 days. The data are reported on individual forms, and OPS compiles the information in three distinct databases. Each of the pipeline databases have similar but varying cause codes to record failures of the three types of pipelines. About 25 percent of the forms filed in the databases show "other" as the reported cause. This code is often used on pipeline forms to report releases that have occurred as a result of natural disasters, such as a flood or landslide, or when the cause could not be determined within the required reporting period. OPS is revising the forms used to collect data for the three databases in an attempt to improve the accuracy and detail of the data collected.